To compare Computed Tomography Perfusion (CTP) RAPID estimated core volume (CV) accuracy in different time frames with diffusion weighted imaging (DWI) infarct volume (IV).

The CTP RAPID is widely used in patient selection for mechanical thrombectomy (MT) after anterior circulation large vessel occlusion (ACLVO). There is a notion that CTP overestimates the CV in early time window from last known normal (LKN).  

Charts of MT cases with ACLVO and TICI 2b/3 reperfusion from 2017- 2019 were reviewed. CTP time was dichotomized as 0-3 hours and ≥3 hours from LKN. DWI IV was calculated by ABC/2 formula. The volumetric difference (VD), defined as DWI IV minus CTP CV, core volume overestimation (CVO), defined as CTP CV minus DWI IV and CT ASPECTS was calculated. Large CV was defined as ≥50 ml. mRS at 90 days were reviewed. Independent sample T-test was performed.

Total MT cases (n) were 61. Mean age was 66±13.9 years. In < 3 hours window from LKN (n 27), mean VD was 0.1±58.3 ml (p 0.99) and CVO (n 11;40.7%) was 39.6±35.7 ml (p 0.008). Mean large CV (n 8) was 78.3±25.4 ml with median CT ASPECTS of 8 (IQR 6.5-9) and median mRS at 90 days was 2 (IQR 0.8- 3.3). In ≥3 hours window from LKN (n 34), mean VD was 46.5±61.8 ml (p 0.002) and CVO (n 5;14.7%) was 25.2±41.27 ml (p 0.60). Mean large CV (n 5) was 116.8±75.3 ml with median CT ASPECTS of 6 (IQR 5-7) and median mRS at 90 days was 5 (IQR 4- 6).

CVO on CTP RAPID was seen in >1/3^rd cases in <3 hours window from LKN, where large CV had higher CT ASPECTS and good functional outcome. Whereas CTP in ≥3 hours window from LKN showed lesser CVO with reliable data for prognosis of functional outcome.